Process of manufacturing calcium.



UNITED TATES" PATENT oFFioE.

I PROCESS OF MANuFAoTuniflefohnolumr Specification of Letters Patent.

rammed Nov. 28, 1905.

Application filed January 20, 1903. Serial No. 139,821.

T0 aZZ whom it may concern.-

.Be it known that we, OTTO-RUFF, doctor of philosophy, a subject of theGerman Emperor, residing at 21 Thomasinsstrasse, Berlin, and WILHELMPLATO, chemist, a subject of the King of Prussia, German Emperor,residing at Colberg, Province of Pommern, Kingdom of Prussia, GermanEmpire, have jointly iu- I vented'new and useful Improvements inProcesses of Manufacturing Calcium, of which the following is aspecification.

..This invention relates to the process of manufacturing calcium metalby means of electrolyzing calcium chlorid, and has for its object torender the process more expeditious same.

Referring to the drawings in detail, a is a crucible of any, suitableform.

I) is the electrolyte.

c is a diaphragm placed between the electrodes d and e.

We have found that the manufacture of calcium metal by electrolysis maybe carried out very expeditiously if one subjects to electrolysis amolten mixture of calcium chlorid and such salts of calcium as arecapable of lowering the melting-pointof calcium chlorid, the latterbeing at about 780 Celsius. Such salts of calcium are all salts thatwill not form with calcium chlorid isomorphous mixtures, We prefer suchsalts of calcium that are not decomposed by being heated to themeltingpoint of calcium chlorid or calcium chlorid containing the saidsalts and will not give basic substances under said conditions. We havefound the following salts of calcium as the most suitable for carryingout our process: calcium sulfate, calcium iodid, calcium bromid, calciumfluorid. We" prefer to use calcium fluorid, although we have found alsothe other-calcium salts being capable of lowering the melting-point ofcalcium chlorid to be suitable for our process. By adding cal-' ciumfluorid to calcium chlorid we may attain a lowering of the fusion-pointof the calcium chlorid by 120 Celsius, according to the amount ofcalcium fluorid added. By small additions of calcium fluorid we obtain asmall lowering, by large additions, a' larger, the maximum being 120Celsius. We may also use mixtures of the said salts. For instance,

we may electrolyze calcium chlorid containing calcium tiodid and calciumfluorid. The said salts of calcium render the molten mixturesufficiently heavy in order to enablethe calcium metal obtained in ourprocess to ascend to the surface of the meltingmass. It is important toavoid the presence of silicious mattersas silicates, for.- instanceas inthe presence of the said substances calcium silicid may be formed thatwill prevent the calcium particles to unite themselves and to formcoherent globules. It is necessary to carry out the 'electrolyzing ofthe molten mass containing calcium chlorid and the other said calciumsalts at temperatures above the meltingpoint of calcium meta1z'-. a,above 700 Celsius, preferably about 760 Celsius. has been found thatmaintaining a temperature abovethemelting-point of calcium, now found at780 Celsius,will cause a diminution of the yield ofcalcium, whereas alower temperature causes a porous mass of metallic calcium nearly to themelting-point we obtain the metallic calcium .in a molten state swimmingon r the surface of the bath. fIt is, however, suitable not to usetoohigh a temperature. being apt to effect a vaporization of calciumduring electrolysis, in order to avoid a combustion and vaporization ofthe calcium metal obtained. The skilled workman will find thetemperature suitable for carrying out our process easily by experiments.It is required to employ asuitable high density of electric- We may, forinstance, mix

The proportions of the calcium salts to be added to the calcium chloridmay vary according to the depression of the melting-point of the calciumchlorid required. The skilled workman will-find the proportions byexperivments. We have found a proportion of about tvglenty per cent.calcium fluorid as very suita e.

For illustrating the manner of carrying out our process we shalldescribe the following example: We place one kilogram calcium chloridand one hundred and sixty-five grams calcium fluorid into a suitablevessel and effect the melting of the mixture, for instance, by heatingwith an electric current. The meltingpoint of the mass will be about at655 Oelsius. The specific gravity of the molten mass will be about 2.5.Now we subject the mass to electrolysis by allowing an electric currentto pass through the mass. We use, for instance, as negative pole anelectrode of iron the dimensions of which are adapted to the usedintensityof electric current, so that the lower part of the electrodemay be heated to red heat, butbelow bright white heat. As positive polewe may use a carbon electrode. We separate the two electrodes by meansof a partition of suitable materialfor instance, iron, which is immersedinto the molten mass. We may use any other suitable material for theelectrodes. For instance, we may form the positive pole from nickel. Wemay use several electrodes instead of one. We may also use severalnegative electrodes and only one positive electrode. We preferto use ahigh density of electric current in order to avoid the formation ofsubchlorid of calcium during electrolysis.

The proportional active areas of the cathode and anode surfaces may beat the beginning of the process as one to two hundred and may vbeincreased according to the increasing amounts of the calcium separated,so that they will be one to twentyor one to ten.

Although we may use any suitable construction of vessels, we prefer touse such having interiorly a device for heating the mass from theinterior by means of electric alternating current or electric continuouscurrent and as may be cooled from the exterior. Muthmame has describedsuch vessels. (See Lz'ehz'gs Annalen, Vol. 320, page 281, especiallyPlate 1.)

The calcium metal will melt on the cathodes as a globule and may bebrought on the surface of the melt, where it may be separated by meansof wire ears or in any suitable manner.

By our process we succeed to obtain calcium metal in a coherent stateinstead of the porous state obtained by the known processes and with'ahigher yield.

What we claim as our invention, and desire to secure by Letters Patent,is-- 1. Process of manufacturing calcium metal consisting inelectrolyzing calcium chlorid containing only additions of calcium saltswhich are capable of depressing the melting-point of calcium chlorid.

2. The process of manufacturing calcium metal consisting in meltingcalcium chlorid containing only additions of calcium salts which arecapable of depressing the meltingpoint of calcium chlorid andelectrolyzing the molten mass.

3. The process of manufacturing calcium metal consisting in meltingcalcium chlorid containing only additions of calcium salts which arecapable of depressing the meltingpoint of calcium chlorid andelectrolyzing the molten mass while maintaining the temperature abovethe melting-point of calcium metal.

4:- The process of manufacturing calcium metal consistinginelectrolyzing calcium chlorid containing calcium fluorid.

5. The process of manufacturing calcium metal consisting inelectrolyzing calcium chlorid containing calcium fluorid, whilemaintaining the temperature above the melting-point of calcium metal.

6. The process of manufacturing calcium metal consisting inelectrolyzing calcium chlorid containing calcium fiuorid and othercalcium salts which are capable of depressing the melting-point ofcalcium chlorid.

7 The process of manufacturing calcium metal consisting in electrolyzingcalcium chlorid containing calcium iiuorid and other calcium salts whichare capable of depressing the melting-point of calcium chlorid whilemaintaining the temperature above the melting-point of calcium metal.

In witness whereof we have hereunto set our hands in presence of twowitnesses.

OTTO RUFF. VVILI-IELM PLATO.

Witnesses:

HENRY HAsPER, WOLDEMAR HAUPT.

